I'm running 2.5" Piping from half of the downpipe to the rear with 2.5" exhaust and high flow cat. Can't really go bigger on the exhaust because of my custom setup. I'm pretty sure the tune is good, because my tuner is really reputable on boosted hondas and Rally cars. I don't have the Crome tune available, but let me see if I can get it from my tuner. Thanks for the help!